Suturing is an integral part of surgery. It is used to hold tissues together or to secure prosthetics (including but not limited to, heart valve prosthetics, annuloplasty rings, vascular grafts, and orthopedic implants) to native tissue. Sutures have conventionally been used to fasten such implants. The suture material is passed through the native tissue and then through part of the prosthetic or adjacent native tissue. The two are then drawn and secured together by tying a knot on the end of the suture.
By way of example, heart valve replacements and prostheses have been used for many years and many improvements in both the functionality and ease of implantation have been made thereon. More precisely, during conventional heart valve replacement surgery, sutures are placed in the native annulus after removal of a damaged native valve. Often small pledgets are threaded on the sutures to buttress their contact with the native tissue. The suture is then inserted through the suture ring of the replacement heart valve. Knots are then tied on the sutures to secure the replacement heart valve to the native heart annulus in its desired position such that there will be no leakage around the replacement heart valve.
When it is recognized that each of the completed knots used to secure the replacement heart valve to the native annulus is actually composed of six or more individual knots, it will be appreciated that this task would take a surgeon a significant amount of time to secure the replacement heart valve into position. Further, with the increased level of difficulty associated with this process, comes an increase in the likelihood of error by the surgeon. In addition, since the incision must be larger and the procedure requires greater time, the patient is exposed to collateral risk factors (which include, but are not limited to, an increased incidence of infection, hypothermia, and fluid loss).
Traditionally, the conventional prosthetic attachment procedure has required the surgeon to possess great dexterity and to be in close proximity to the knot. Emerging minimally invasive surgical techniques add an extra level of difficulty to this task since the incisions associated with such methods are generally much smaller than in conventional surgery. As a result, surgeons are required to spend more time tying off the sutures, or in some cases are required to stretch the incision in order to complete the task. By requiring the surgeon to make larger incisions to gain access to tie these knots, the advantages commonly associated with these minimally invasive surgical procedures, of quicker healing, less disruption to surrounding tissues, and less likelihood of infection, are jeopardized.
Sensitive to these new demands, methods and apparatus for implanting heart valve replacement apparatus under minimally invasive conditions have been developed. Examples of such replacement apparatus and methods for implanting heart valve replacement apparatus have been disclosed in U.S. Pat. Nos. 4,655,773; 4,364,126; 4,204,283; 3,898,999; 3,996,623; 3,859,668; 3,534,411; and 5,776,188. Indeed, apparatus and methods have been disclosed that avoid the use of sutures altogether. For example, U.S. Pat. No. 3,143,742 discloses spacing curved pins along the circumference of the apparatus to pierce the tissue of the native annulus of the heart at the desired attachment point. Unfortunately, due to vagaries in the native tissue, good coaptation along a geometrically perfect surface is not always possible.
Novel technologies have been deployed for the purpose of sewing heart valve subcomponents together. U.S. Pat. Nos. 5,071,431; 4,863,460; and 4,743,253 each use a ductile or deformable locking ring as a means to bind the various subcomponents of the heart valve device. However, the aforementioned approaches do not avoid the securing of the implant to the native tissue without the use of traditional suturing methods.
Recently, medical instruments have been developed, which permit surgeons to manipulate sutures through a small opening. However, these instruments, which provide an extension between the surgeon's hands and the suture, are cumbersome, thus impeding the surgeon's ability to appropriately place the suture knot.
In response to this problem, surgeons have sought alternatives to conventional knot-tying techniques. Various sutures and suture terminating devices have been disclosed. The most frequently disclosed among these alternatives is the use of surgical clips, which are designed to replace suture knots.
Examples of surgical clips to terminate sutures have been disclosed in a number of patents including U.S. Pat. Nos. 3,976,079; 5,282,832; 5,078,731; 5,474,572; 5,171,251; and 5,409,499. In general, these devices contain locking mechanisms which require the surgeon to deform the device on the suture's path and entrap the suture material in the clip. The suture is fixed in a single location and thus the necessity of tying a knot on the suture is avoided. These devices are problematic because they require actuation and, more importantly, pinpoint accuracy by the surgeon since they are not adjustable.
Still other configurations of surgical clips are disclosed in U.S. Pat. Nos. 5,078,731; 5,474,572; 5,171,251; and 5,409,499. These clips are also actuated by the surgeon's deformation of the device. The locking mechanisms in these devices are incorporated into the device's body. However, lateral access is required in order to actuate these clips. This cumbersome configuration makes them difficult, if not impossible, to incorporate into prosthetics. Further, these clips also lock the suture into a single position once actuated. This abridges the surgeon's ability to further adjust the tension on the suture, thus requiring the surgeon to remove the suture and repeat the process in order to achieve, when necessary, better coaptation of the tissue by the suture.
Still other surgical clips are disclosed in U.S. Pat. Nos. 3,976,079 and 5,282,832. Both of these clips incorporate an additional mating component (retaining clip 96 and retainer 120, respectively), which when attached to the clip locks the suture in place. However, the use of small loose parts is highly undesirable since it is easy to drop and lose such pieces through a minimally invasive incision. Indeed, if this were to occur, for example, inside a patient's heart, the potential for an arterial embolus and patient injury would greatly increase. Again, these clips, like all the aforementioned clips, lock the suture into a single position, which, as discussed above, has many disadvantages.
Additionally, modifications of sutures and surgical ties have been disclosed in U.S. Pat. Nos. 5,123,913 and 4,955,913. The methods presented in these patents include the use of a modified suture or surgical tie having serrations or ridges on the suture's or tie's bodice, which when mated with the appropriate closure device, the suture or tie is allowed to be freely advanced towards closure and cannot slide backwards. This allows the surgeon to incrementally increase the tension on the suture or tie without the need to tie a knot. These modified sutures/ties are not suitable for most surgical applications, since they can not be passed through tissue or prosthetics like a standard suture. In addition, neither of these devices afford the surgeon with the opportunity for precise tightening of the suture or tie since the serrations or ridges are incremental. Further, U.S. Pat. No. 5,123,913 discloses a modified suture terminating with a loop member which is designed to mate with the serrations along the length of the suture. While this will function as a surgical suture, the loop member increases the length of the device, making it unsuitable for certain surgical applications, such as securing a heart valve inside the heart. Additionally, these inventions are not compatible with standard sutures.
U.S. Pat. No. 5,776,188 discloses three pertinent apparatus for securing a suture without a knot to a heart valve sewing ring. In the first apparatus, plugs 192 (as illustrated in FIG. 5) have been credited as devices which help secure the suture in place. This is similar to the suture clip methodology which was discussed above. The drawbacks associated with these plugs are that they: (1) do not eliminate the need for a knot to be tied, (2) do not allow the tension to be incrementally adjusted on the suture, (3) have the potential to dislodge causing patient injury, and (4) may be difficult to position in a minimally invasive cardiac procedure.
The second apparatus provided by U.S. Pat. No. 5,776,188, incorporates the use of ball 248 and chamfered slot 242. As illustrated in FIG. 7, the ball and slot cooperate to effectuate the securing of sutures to a heart valve sewing ring without the necessity of a knot. While this embodiment may fasten a suture to the valve sewing ring, it is undesirable to surgeons for a number of reasons. First, this embodiment utilizes a free-floating piece (ball 248) which has the potential to dislodge or jam. Consistent with the concerns raised above, relating to U.S. Pat. Nos. 3,976,079 and 5,282,832, if the ball were to dislodge from the device, it could harm the patient. Further, although this embodiment may engage the suture, the rounded nature of the ball will minimize the field of contact and the resulting integrity of the grip thereon. This greatly reduces suitability for such a device since most surgical procedures require a strong and permanent grip.
The final apparatus disclosed within U.S. Pat. No. 5,776,188 relies on pressure generated by spring 252 to secure the suture. More particularly, spring 252, which is a small separate piece attached to the device, impedes the sutures movement by trapping it. Therefore, the stronger the spring used, the more pressure it applies to the suture and the more reliable its grip will be. However, as the pressure increases, the surgeon's ability to adjust or fine tune the tension applied to the suture is hampered. In addition, the strength of the grip is directly dependent upon the spring's stamina and strength. Further, consistent with the above discussion relating to the previous apparatus, spring 252 is not captured within the body of the device; accordingly, it is capable of breaking free from the device which could cause patient injury.
As will be more fully appreciated below, none of the aforementioned devices offer the ease and versatility for terminating sutures and thus securely locking tissues and/or prosthetics in place, as the instant invention. Indeed, the instant invention provides a means for securing tissues to native tissues and prosthetic implants to native tissue; the benefits of which may be most appreciated in operations where minimally invasive procedures are utilized.
The apparatus and systems disclosed herein obviate the need for manually tying knots, a procedure which typically requires the surgeon to manipulate his hands in tight proximity of the tissue being secured. This invention may be used as a freestanding device or may be incorporated into prosthetic implants such as heart valves, annuloplasty rings, orthopedic implants or the like, all of which require securing to native tissues.
Moreover, the devices of the instant invention are applicable to all instances of operative procedures where the surgeon needs to secure tissue with a suture, but has limited access for her/his hands to tie a knot. In instances of using sutures to stop bleeding or securing tissues or implants in mi ally invasive procedures, the devices of the instant invention will facilitate the procedure by eliminating the time and physical exposure required to manually tie knots to terminate the suture. The present invention's advantages of enhanced tissue securing with minimal surgical exposure, decreased implementation time, and enhanced reliability are accentuated when compared to existing related technology.